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US 6,091,941 AGranted
Radio apparatus
AssigneeFujitsu Limited
InventorsYukihiro Moriyama, Yuji Kaneko, Koji Takata, Masaru Kabashima
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AssigneeFujitsu Limited
InventorsYukihiro Moriyama, Yuji Kaneko, Koji Takata, Masaru Kabashima
Estimating the term…
Disclosed is a radio apparatus in which modulating signals (I, Q signals) from an arithmetic/control unit are converted to analog signals, which are then applied to an orthogonal modulator. A modulated wave for transmission, which has been produced by orthogonally modulating a reference carrier wave by the modulating signals, is demodulated by the orthogonal detector. The arithmetic/control unit compares the modulating signals and the demodulated signals and, based upon the comparison, updates distortion compensation coefficients and applies pre-distortion processing to the modulating signal using the distortion compensation coefficients. Leakage carrier produced due to offset of the orthogonal modulator is detected and the arithmetic/control unit adjusts the level of the modulating signals or shifts the phase of the reference carrier wave in such a manner that the leakage carrier (offset) becomes zero.
A radio apparatus for subjecting a modulating signal to pre-distortion processing using distortion compensation coefficients which correct distortion of a transmission power amplifier, amplifying, by the transmission power amplifier, a carrier wave obtained by being digitally modulated by the modulating signal that has been subjected to the pre-distortion processing, transmitting the amplified carrier wave, comparing the modulating signal with a demodulated signal, which is obtained by branching and demodulating the transmitted carrier, and updating the distortion compensation coefficients, said apparatus comprising:
Dependencies are inferred from the claim text.